wgn's julian crews is live at mccormick place with details. julian? >> much has been said about the chicago marathon being an economic engine. witho out of town runners many come from around the world filling up hotels and restaurants. it is also an economic engine for nonprofit organizations. >> there are so many spectators at the chicago marathon. they're on the sidelines. they're cheering. when they see us wearing jerseys it helps build brand awareness. >> organizations here to help get the word out. there have runners letter-writing. they are raising pledge money. the health market their brand and get the word out about their organization. 20 percent of the 45,000 people that are in the marathon are participating with some sort of a charitable organization. many of these organizations are well established that there are also some grass roots organizations. there's a group here running for a fallen navy seal by the name of david jon larson. his loved ones have pulled together a memorial fund. he was also a standout soccer player in high school as w